APPLICATION NOTE – Fire Investigation
THE ART OF GC-MS FOR FIRE INVESTIGATION PORTABLE GC-MS UNITS LIKE THE G510 CAN CONFIRM SUSPECTED ACCELERANTS ON-SCENE
SUMMARY Fire investigators rely on a variety of tools to assist them in their mission to determine the cause and origin of a fire. At times, interpreting the results produced by those tools can be as much art as it is science. Fire investigators are detective, scientist, engineer, and law enforcer all-in-one. So, when and where can a gas chromatograph mass spectrometer (GC-MS) aid them in their mission? A portable GC-MS can be used to confirm the presence of a suspected accelerant immediately on-scene to better inform action plans.
FIRE SCENE INVESTIGATION After a fire scene is determined to be safe, fire investigators begin with a visual assessment of the area. They look for burn patterns or suspicious areas that may indicate the origin of the fire. But the next step is to determine - how did it start? Figure 1: FLIR Griffin G510 Portable GC-MS If the burn patterns or visual clues indicate an accelerant might have been used, the scene will likely be treated as suspicious and investigators will work to confirm the presence of an ignitable liquid. A portable GC-MS, like the FLIR Griffin™ G510 (Figure 1), can be used to confirm the presence of a suspected accelerant immediately on-scene. GC-MS is a gold-standard technology used both inside and outside of labs to analyze complex samples, like fire debris. It is a selective and sensitive tool that offers the broadest chemical detection capability. It is the ultimate confirmatory tool. Results can be produced in just a few minutes, expediting decision-making at the point of sample collection. On the fire scene, the investigator can collect a sample from the fire debris and perform either a liquid extraction or solid-phase microextraction (SPME), before introducing it to the injector on the GC- MS. In addition to a standard injector, the FLIR Griffin G510 is equipped with an air sampling probe for extra utility at the fire scene. The GC-MS identifies any constituents found present in the sample Syringe injection performed on Griffin G510 mixture. An expert in the field uses this chemical signature to determine the identity of an accelarant. Once an accelarant is confirmed, the investigator has the information needed to collect evidence for further investigation. This application note demonstrates semi-volatile hydrocarbon analysis using the FLIR Griffin G510 portable GC-MS. DETECTION METHODS AND RESULTS Figure 2 and Table 1 contain results from a single syringe injection, which identifies C9 through C28 hydrocarbons. For additional fidelity, customers can use Griffin Match Factor (GMF) technology, which combines NIST mass spectrum library matches with retention indexing to provide additional confidence. This is particularly helpful when analyzing similar chemicals. Figure 4 shows the C20 C24 different chromatographic signatures of Kerosene C14 C16 C18 C10 C12 C26 (a common accelerant) as it breaks down (or weathers) C28 over time. Accelerants can often be matched to sources based on these weathering patterns.
# Target CAS # Ret. Time (min) C9 Nonane 111-84-2 3.33 Figure 2: GSS Touch results for C9-C28 n-alkane mixture C10 Decane 124-18-5 3.98 C11 Undecane 1120-41-4 4.58 C12 Dodecane 112-40-3 5.13 C13 Tridecane 629-50-5 5.65 C16 C14 Tetradecane 629-59-4 6.11 C15 Pentadecane 629-62-9 6.58 Unweathered Kerosene C16 Hexadecane 544-76-3 7.01 C17 Heptadecane 629-78-7 7.42 C18 Octadecane 593-45-3 7.8 C19 Nonadecane 629-92-5 8.17 C16 C20 Eicosane 112-95-8 8.52 25% Weathered Kerosene C21 Heneicosane 629-94-7 8.87 C22 Docosane 629-97-0 9.19 C23 Tricosane 638-67-5 9.51 C24 Tetracosane 646-31-1 9.84 C25 Pentacosane 629-99-2 10.22 C16 C26 Hexacosane 630-01-3 10.63 50% Weathered Kerosene C27 Heptacosane 593-49-7 11.14 C28 Octacosane 630-02-4 11.78
Table 1. Retention times for the hydrocarbons identified C16 SUMMARY 75% Weathered Kerosene The results from this study indicate the FLIR Griffin G510 is capable of field analysis of ignitable liquid residues at a fire scene. In suspected arson cases, crime laboratories can take six months or longer (depending on caseload) to Figure 4: GSS Touch results for weathering across a series of Kerosene samples provide a confirmatory indication that accelerants were used, highlighting the need for rapid on-site analysis tools like the FLIR Griffin G510. The ability to confirm the presence of suspected accelerants at the point of sample collection enable fire investigators to streamline decision making regarding evidence collection and processing.
For more information, please visit: www.flir.com/g510 DETECTION SALES, AMERICAS FLIR Systems, Inc. 1201 S. Joyce Street Suite C006 Arlington, VA 22202 Phone: +1.877.692.2120 [email protected]
Equipment described herein is subject to US export regulations and may require a license prior to export. Diversion contrary to US law is prohibited. ©2019 FLIR Systems, Inc. All rights reserved. 19-1598-DET-FIRE 07/03/19